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Tank leak on seam -- What to do?

Hello all, I got a doozy here. My tank leaks on the drivers side at the front right along the seam. Given the rust prevelent in the rear of the car and the scope of the repair, I'm not sure its worth swapping tanks.

Does it work to put a bunch of tank repair goop all around the outside of the seam? What about reaching in through the sending unit hole and sealing it from the inside?

My experience with gas tank sealants from the inside required the removal of the tank. The sealant was put in through the filler neck and then the tank was rolled and turned upside down in all directions to distribute it over the entire interior surface. It worked well for me, in this case on a beater car that I wanted to put little money into. In your case, if you need to pull the tank to do it, it makes more sense to just replace it with a used tank or a new one. Regardless which way you go, with the high price of fuel, and the even more important safety concerns of a gasoline leak, get it fixed! Good Luck!

In your case, if you need to pull the tank to do it, it makes more sense to just replace it with a used tank or a new one.

That's definitely the crux, pulling the tank. All the bolts on the exhaust are rusted solid, the driveshaft bolts are frozen, the rear tranmission crossmember bolts look horrible as well, and so on. The same salt that ate the seam on the tank, ate the rest of the undercarrige too.

In other words, pulling it aint gonna happen.

So I'm left with sealing the tank from the inside, or sealing it from the outside.

Hello all, I got a doozy here. My tank leaks on the drivers side at the front right along the seam. Given the rust prevelent in the rear of the car and the scope of the repair, I'm not sure its worth swapping tanks.

Does it work to put a bunch of tank repair goop all around the outside of the seam? What about reaching in through the sending unit hole and sealing it from the inside?

Don't Pick up Smoking near the car you may be able to get in through the sending unit hole... but it's a tight squeeze in there

Well, it's certainly worth a shot to try and fix it from outside. I think I'd run it low on gas, then clean the seam real good down to bare metal, then rough it up with some 60 grit paper, then clean it with a good solvent like brake cleaner or acetone or MEK or something, then put on a layer or two of JB-weld, maybe with some fiberglass cloth. I'd make a big patch, at least an inch past the seam. Seems like this should work, for awhile anyway.

I'm just spit balling here, I've never repaired a rusted out gas tank. But even commom sanding paper can cause sparks. How about "wet sanding" with a waterproof sandpaper or emery paper. That might add an extra margin of safety. I would guess that you'll have to drain the tank absolutely dry, or at least below the level of the leak. I don't think you'll get a good bond with the JB weld if the leak is "active".

JB Weld will not seal a leaky gas tank (or much else for that matter).

POR15's POR-patch sealant WILL permanently seal a tank from the outside. I've used it for this purpose--it really works. Here's what to do:

Run the tank down. Scrape/scuff/clean the area. Use some solvent to degrease and remove any trace of fuel.

Squeeze the POR patch into the seam/hole. Force it in so that it is at least doing more than just sitting on top of the leak.

It takes a minimum of 72 hours to completely cure. While it's drying, make sure to leave the gas cap off so that the captive fuel vapors dont try to escape through the wet sealant, forming tiny holes in it as it dries.

You may want to apply a second layer of sealant within 24 hours of the first. This is just a little insurance in case you missed a spot...

So these are just fuel tanks that reside in the trunk? Does my regular fuel pump work in that type of setup?

Thx for the replies guys...

Sure - normal fuel pump will work fine. Just have to do a little modification with the hose routing, and filler tube etc. All-in-all there's a bit more work involved, but the advantages are clear of course. Especially if you are into off-roading, as the fuel tank is pretty exposed down there.... Personally for what a lot of yards want for a fuel tank, the cost of a plastic fuel cell is well worth a few extra bucks and some small headaches. Your tank is already rusting out, and even if you fix the leak at the seam, you have to wonder how much rust and scale is in the tank and will start flaking off into your fuel system in the near future.....

Also it sounds like your car is pretty much on it's last owner. So if you do the fuel cell you will be able to salvage it for resale or for your next terribly rusted hulk. Being plastic it will never deteriorate, and could be used again and again with many vehicles.

JB Weld would work. You would need to prep the surfaces well, and allow it to dry for at least 48 hours I would say before using the car. When dry it is impermeable to gas and oil, and it will bond with solid (not rusty) metal extremely well. I've seen people seal cooling systems with it. Those are pressurized, your fuel tank is not. Those who say it won't work did not prep their surfaces well, did not mix it properly, or (most common) did not allow it to set up long enough. It will continue to harden for about 72 hours I've noticed.

Looks like a novel idea compared to pulling the tank. Anyone do this job?

Looking into this for a '97 OBW that has the pesky fuel leak at the tank inlet (already fixed the leak at the rotten fill pipe, which by pulling on the inlet hose during removal of the fill pipe probably made the inlet begin to leak or get worse...)

Looks like a novel idea compared to pulling the tank. Anyone do this job?

Looking into this for a '97 OBW that has the pesky fuel leak at the tank inlet (already fixed the leak at the rotten fill pipe, which by pulling on the inlet hose during removal of the fill pipe probably made the inlet begin to leak or get worse...)

Kudos for using the search function, but you might be better off starting a new thread instead. This thread is six years old.

If mounted and plumbed right it should be rollover safe. Will offer the car for crash testing at the right price.

The thought of dropping the tank in my driveway fills me with...rust flakes in the facial orifices...doesn't sound like fun although only one bolt sheared off on the filler neck job so how bad could it be? One can only run on the 'only fill half way option' for so long...

JB Weld would work. You would need to prep the surfaces well, and allow it to dry for at least 48 hours I would say before using the car. When dry it is impermeable to gas and oil, and it will bond with solid (not rusty) metal extremely well. I've seen people seal cooling systems with it. Those are pressurized, your fuel tank is not. Those who say it won't work did not prep their surfaces well, did not mix it properly, or (most common) did not allow it to set up long enough. It will continue to harden for about 72 hours I've noticed.

GD

JB weld does not work on fuel tanks with the new ethanol blend gas. I used to use it on the tanks in my various woods beaters and never had a problem. Now, it works for a month or two and starts leaking again. After that you can peel the patch off with a putty knife leaving bare steel underneath. JB recommends their water-weld for gas tanks rather than the standard stuff you normally use. I don't know if it works any better, but I'm sick of having tanks not stay "fixed".